In 630, Eanswith founded the BenedictineFolkestone Priory, the first nunnery in England. She was supported in this by her father, Eadbald, who ruled as king of Kent from 616 to 640 CE.

While the monastery was under construction, a pagan prince came to Kent seeking to marry Eanswythe. King Eadbald, whose sister St. Ethelburga married the pagan King Edwin two or three years before, recalled that this wedding resulted in Edwin's conversion. Eanswythe, however, refused.

Around 630, the building of the monastery was completed. This was the first women's monastery to be founded in England. St. Eanswythe lived there with her companions in the monastic life, and they may have been guided by some of the Roman monks who had come to England with St. Augustine in 597. She remained at the abbey until her death and was later canonized by the Catholic Church.[1]

Saint Eanswith's day falls on September 12. Traditionally, this is the date on which her remains were translated to the new church in 1138.

In 1885 human remains were discovered in the church wall at the Folkestone parish church, dedicated to "St Mary and St Eanswythe" which may have been those of Saint Eanswith.